Error Message & can't see Ortho drawings in Project manager

[Anonymous]

I have just had a problem with Plant3D 2011.

When I start up the software and go to open my project I can see (and open) all of the files on the "Source Files" tab of the project manager however when I go to the "Orthographic Drawings" tab most of my drawings have disappeared and sometimes I see an Error message that says "Microsoft.NET Framework-Unhandled exception--- An item with the same key has already been added"

Anyone had similar issues and any idea how I recover from this situation.

Although I can't see the Ortho drawings I know they are still there by checking file manager and I even tried to "link drawing to project" but that won't work as it says the drawing already exists.

Attached is the wording from the error message.